Then the democrats should have passed legislation targeting the root of the college affordability problem, not a one-off. This legislation doesn’t solve anything.
This policy doesn't solve the whole problem, but it is a step in the right direction. Consider it a proof of concept: if this policy can show the feasibility of forgiving existing student loan debt that's piled up over many decades, then it should pave the way for future policies which can better subsidize new loans -- a far lower cost.
Obviously, the root of the problem lies with privatization of education and capitalism, but those are things so ingrained in our society that we basically can't expect to ever fix them. Working our way towards better subsidies is the next best goal.